Hypothyroidism in Shar-Pei dogs
Does your Shar-Pei seem to have changed its behavior? Does it look different? Does it exhibit clinical symptoms or are some lab results inexplicable? 

Such changes could be signs of an underactive thyroid termed hypothyroidism.

Many Shar-Pei owners and vets do not immediately recognize subclinical activity, because the disease develops sort of in the background. The result is that the affected animal often does not get the necessary treatment, because the problem is not diagnosed!

Hypothyroidism is by far one of the most common diseases of the thyroid affecting dogs of all ages. Most dogs suffering from an underactive thyroid are between one and six years-of-age. The clinical syndrome of hypothyroidism (or an underactive thyroid) has the following general symptoms: 

•    The Shar-Pei is inattentive and ignores its normal environment. It tends to be sluggish!
•    It appears frightened and is easily stressed.
•    The dog sleeps a lot and is no longer adequately active. Its physical condition deteriorates. 
•    It becomes weak!
•    It is easily chilled.
•    It acts aggressively at times.
•    The Shar-Pei fattens easily, without overeating or getting a new diet.
•    Hair and skin changes are noticeable. The coat becomes fatty, greasy, and dull, with significant scaling. Loss of hair may occur, with bald spots showing up, and the pigmentation may change. The skin tends to feel very dry and rough.
•    Secondary infections are common, such as a hard to treat ear infection (otitis externa).
•    The vet finds that your Shar-Pei has an irregular heartbeat (cardiac arrhythmia). 
•    It has elevated cholesterol levels.
•    The dog’s liver enzyme levels are elevated.

A Shar-Pei suffering from hypothyroidism will likely show one or more of the above symptoms, while not all will appear simultaneously. However, the thyroid function level cannot be determined just from the observed symptoms.

The thyroid is one of the most well-known hormone glands wherein dysfunctions are quite common, and hence it is critical to be aware of this endocrine gland's function and role.

In dogs, this gland comprises two organs and is situated to the left and right of the trachea (windpipe), close to the larynx roughly between the first three to eight tracheal cartilaginous rings. Normally, one can't feel the two organs connected by a narrow I band (isthmus of thyroid), unless the gland is swollen.

The thyroid is a part of the regulatory feedback loop responsible for producing hormones. This mechanism comprises the hypothalamus, hypophysis (or pituitary gland) and the thyroid. The hypothalamus produces TRH (thyrotropin-releasing hormone), which stimulates the anterior pituitary gland to release TSH (thyroid-stimulating hormone). The level of TSH triggers synthesis of the T3 and T4 (triiodothyronine and thyroxine) hormones in the follicular cells, which then reabsorb the hormones and release them into the bloodstream.

The thyroid is responsible for more than just metabolic and neuronal activity of every cell in the body. The hormones it produces have a widespread effect on the animal's growth and health. The higher the concentration of the hormones, the higher the rate of metabolism, and consequently the metabolic activity of the entire organism. On the contrary, lack of this hormone in young animals, for instance, tends to retard their mental and physical development.

<< Start < Prev 1 2 Next > End >>
Canine Hypothyroidism
Page 2 of 2

As stated previously, this illness can be overlooked early on since it has no noticeable clinical symptoms. Progressive loss of thyroidal function causes the disease to develop slowly and insidiously. Hence its gravity is often underestimated, and even experienced owners can easily miss it. That is why it is referred to as subclinical activity, meaning that changes in laboratory findings are not necessarily accompanied by noticeable symptoms.

If you suspect a subclinical state of hypothyroidism, take the dog immediately to a vet. More advanced hypothyroidism showing clinical symptoms should always be treated.

Insufficiency of a thyroid or hypothyroidism implies an inadequate supply of the T3 (triiodothyronine) and T4 (tetraiodothyronine or thyroxine) hormones. T3 basically stimulates energy development, raises the use of oxygen, accelerates carbohydrate absorption, enhances synthesis of glucose (gluconeogenesis), increases glucose absorption, decreases the rate of glycogen storage in the liver, greatly enhances the breakdown of body fat, increases cholesterol synthesis and breakdown, stimulates protein synthesis, and influences the body’s water balance and bone metabolism. Thus thyroid hormones are indispensable for growth and maturity of the skeleton and brain development.

Since T4 is the less active hormone, this is offset through production of much greater quantities T4 than T3. Iodine is a key trace element necessary for the production of these hormones. Shortage of iodine increases the ratio of T3 to T4. Iodine does not remain in the body, with about 80% of it being cleared by the kidneys through urine and roughly 20% being cleared by the intestines through stools.

Scientists believe that a congenital autoimmune dysfunction is responsible for an underactive thyroid in about 80% of the cases. This disease destroys thyroid tissue, which results in decreased hormonal production. Consequently, the immune system attacks internal substances like T3 or T4. However, very often this autoimmune disorder or thyroiditis is not diagnosed until after the clinical symptoms reach an advanced stage.

Autoimmune dysfunctions always stem from genetic disorders and are hereditary. Hence, any animals destined for breeding should always be tested for hypothyroidism to hinder them from passing on the disease to the next generation. About 80% of the cases of hypothyroidism fall under this category!

Severe hypothyroidism is treated by administering thyroid hormones. However, sometimes the deviations in hormonal levels are minor, and the blood tests show values lying in the lower segment of the normal range. A vet usually prescribes L-thyroxine tablets to treat the illness based on the dog’s condition. The affected dog has to take the medication daily without interruption for the rest of its life.

Hypothyroidism is not curable!

With such treatment and regular checkups, most dogs have a typical life expectancy and can lead a normal life. One sees improvement within the first week of hormonal treatment – in that the dog becomes more active. However, the skin problems linger on a bit longer.

I can not overemphasize what I have said before:

As stated, autoimmune diseases are always caused by genetic defects and are hereditary! Therefore, it is imperative that animals in a breeding pool be accordingly examined. Otherwise they could pass such a the disease on to their offspring.

Hanspeter Kobold
Bremen, November 2007

This material is copyrighted by the author. All rights reserved. Reproduction in any form, in part or in whole, shall require the express prior written approval of the author. The author welcomes suggestions, comments, or criticism of any kind.